This invention relates to a carbon brush for an electric machine, which carbon brush resiliently acts on a collector.
There is already known a great number of various versions of carbon brushes for electric machines. Within a guideway, the so-called brush holder, these carbon brushes are basically arranged so as to be movable radially to the collector which they resiliently act upon. The necessary resiliency is provided by a helical spring which is arranged in alignment with and, relative to the collector, behind the carbon brush. On the side of the brush holder, the carbon brush is generally supported on a wall, e.g., on a bent plate. Separate stranded conductors serve the electric power supply to the carbon brushes. These stranded conductors have to be connected separately in an electrically conductive manner to a power lead. Contacting the flexible stranded conductors to the power lead is a problem in so far as it always takes a great effort to bring the end of the stranded conductor into the desired position. This procedure is not suitable for a cost-saving and, hence, fully automatized assembly with a low percentage of refuse.
Admittedly, resilient brackets with brushes fixed on their ends have already become known which also transport current to the carbon brush so that there is no need for complicated and expensive contacting by means of a stranded conductor. An essential disadvantage of these brush brackets, however, is that, as wear increases, the end of the bracket, together with the brush, will describe a more or less circular movement resulting in oblique abrasion of the carbon brush. Further, in operation, there is a continuous change in the decisive, current-transmitting contact surface. Finally, in operation, the brackets will be caused to vibrate which can imply interruptions in electric power supply.
It is an object of the present invention to provide a carbon brush which will allow easy and cost-saving assembly and which, on the other hand, will ensure the required safety against interruptions in electric power supply.
1. It has been found out that this object is solved by a carbon brush radially movable with respect to the collector and inflexibly connected with a bending leg. It is of advantage that the spring-like leg is connected with the carbon brush so that there is no need for the supply and mounting of a separate spring on the motor assembly line. Further, the carbon brush is reliably guided radially to the collector and, in particular, there will be no oblique abrasion.
Any further advantages and further developments of this invention will become evident from the description of the drawings. In the following, this invention will be described in more detail with reference to one example of an embodiment represented in the drawing.